Synthetic polymer materials possess poor surface properties In particular, most fibers formed from polyester, polyolefin, polyamide and acrylic are not hygroscopic and have poor antistatic, and soil release properties. Many conventional fabrics formed from polyester and polypropylene have relatively poor hand properties. In particular, most polyester and polypropylene have a slick or synthetic fabric feel, as well as being deficient in terms of hygroscopic, antistatic, and soil release properties.
Attempts have been made by the prior art to polymerize a water soluble vinyl monomer onto a polymer substrate. This has proved to be particularly difficult with a polyester substrate or a polypropylene substrate.
The prior art has attempted three approaches to depositing a water soluble vinyl monomer onto a polymeric substrate.
The first approach appears to be by adhesion between the polymerized vinyl monomer and the polymeric substrate. Examples of this approach include U.S. Pat. Nos. 3,377,249 and 3,958,932.
The method of U.S. Pat. No. 3,377,249 employs an aminoplast textile resin to effect adhesion of a synthetic acid emulsion polymer to a polymeric substrate. In the method of U.S. Pat. No. 3,958,932 the vinyl polymer is affixed to the polymeric substrate by the use of elevated temperature curing.
A second approach involves entanglement of the polymer formed from the water soluble vinyl monomer into the substrate. In U.S. Pat. No. 3,926,551 water-insoluble polymers derived from acidic vinyl monomers are formed both on the surface and within polyester fibers. In U.S. Pat. No. 3,995,998 polymers derived from both acidic and non-acidic water soluble vinyl monomers are deposited on both the surface and within the fibers forming the polymer substrate. In U.S. Pat. No. 4,065,256 a composition comprising a liquid organic solvent, and a hydrophobic radical polymerization initiator is used to achieve graft polymerization onto both the surface and within a hydrophobic synthetic polymer substrate. In U.S. Pat. No. 4,238,193, an impregnated initiator is used to penetrate into the interior of a polymeric substrate fiber and to effect polymerization of a water soluble vinyl polymer both onto the surface of and within the substrate.
A third approach has been to chemically modify the polymeric substrate so as to receive the polymer from a water soluble vinyl polymerization. U.S. Pat. Nos. 3,088,791; 3,107,206; 3,115,418; and 3,617,457 each disclose the use of high energy radiation to modify a polymeric substrate. It is believed that the high energy radiation clears the bonds on the surface of a polymer to form free radicals. These free radicals participate in chemical reactions with the vinyl monomer. U.S. Pat. No. 3,088,791 irradiates a shaped organic polymer substrate at low temperatures. U.S. Pat. No. 3,107,206 irradiates a stem polymer that has been swollen with a non-polymerizable swelling agent. U.S. Pat. No. 3,115,418 irradiates a polymeric substrate in the presence of oxygen. U.S. Pat. No. 3,617,457 irradiates a polyester substrate and uses unique water soluble vinyl monomers.
U.S. Pat. No. 3,600,122 employs a spark discharge in a zone of free radical initiating gas to generate free radical sites on the surface of a polymeric substrate. This modified polymeric substrate is further reacted like any irradiated polymer.
U.S. Pat. No. 4,043,753 modifies a conventional polyester substrate by incorporating p-carboxycinnamic acid to replace a portion of a terephthalic acid of the polyester. The resultant polymeric substrate is a modified polyester polymer containing an unsaturated group that is susceptable to graft polymerization.
To the best of my knowledge, the prior art approaches have not yielded a polyester or polypropylene substrate which can be in the form of fibers making up a fabric that will withstand repeated launderings, such as 20 or more launderings in a conventional washing machine. Thus, it is an absolute essential for a satisfactory commercial product that it withstand repeated launderings.
Futhermore, the prior art approaches frequently suffer from undue expense, complex equipment requirements, and other processing shortcomings.